BERTHOLD TECHNOLOGIES Uni-Probe LB 490, Руководство пользователя

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6 Radiation Protection Volume 1
6.3
Mounting the Shielding
6.3.1 Safety Instructions
To keep the radiation exposure of the assembling personnel as low
as possible, only licensed personnel who have been trained on how
to handle radioactive substances are allowed to assemble or disas-
semble the shielding with the source. The work is performed
according to the instructions and under the supervision of the Radi-
ation Safety Manager. It has to be ensured that the lock of the
shielding is closed and secured, so that no unshielded radiation can
exit. Make sure the shielding is not modified or damaged.
Depending on the operation conditions, the function check has to
be repeated at appropriate intervals, and at least every six months.
6.3.2 Radiation Exposure during Installation of the
Shielding
The shieldings of measuring systems are usually designed such
that the limit of the control area is in a given distance (in most
cases less than one meter) around the shielding, and it does not
matter whether point or rod sources are being used and how high
their activity is. A simplified calculation of the radiation exposure
during installation of the shielding is possible with sufficient accu-
racy using the dose rate data printed on the type plate, measured
in 1m distance from the shielding. The radiation exposure D can be
calculated according to the following formula:
D = DR x t x 4
D = accumulated dose during installation in µSv
DR = dose rate on the type plate of the shielding in µSv/h
t = time needed for the installation with shielding in h
If the work process is prepared well, you may expect a working
time of less than 20 minutes to perform work such as installation of
the shielding or operating the shutter.
Calculation example
DR = 3µSv
t = 20min (1/3h)
D = 3 x 1/3 x 4 = 4 µSv/h
If we compare this dose with the permissible annual dose of 1mSv
for persons who are not exposed to radiation on their job, this work
may be carried out 250 times per year by one and the same per-
son.